Single Crystal Growth and Crystal Structure Analysis of Novel Orange-Red Emission Pure Nitride CaAl2Si4N8:Eu2+ Phosphor

Single crystal of novel orange-red emission CaAl 2 Si 4 N 8 :Eu 2+ phosphor was grown by our original vapor phase technique, and the precise crystal structure was investigated for the first time by single crystal X-ray diffraction analysis. The crystal structure of CaAl 2 Si 4 N 8 :Eu 2+ single crystal was verified to be an α-Si 3 N 4 -type trigonal structure (space group P 31 c ) with a = 0.79525(9) nm, c = 0.57712(8) nm, and z = 2. The Ca atoms were coordinated to seven nitrogen atoms and located in the three-dimensional framework formed by (Al, Si)N 4 tetrahedra. The single-crystal CaAl 2 Si 4 N 8 :Eu 2+ phosphors exhibited a broad reddish-yellow emission with a peak at 600 nm under near-UV and blue light excitation. When increasing the temperature up to 150 °C, the emission intensity of the CaAl 2 Si 4 N 8 :Eu 2+ phosphor decreased to 88% of the initial value at 25 °C.